The Lectin Isolated from the Alga Hypnea cervicornis Promotes Antinociception in Rats Subjected to Zymosan-Induced Arthritis: Involvement of cGMP Signalization and Cytokine Expression.

This study investigated the effects of the alga lectin Hypnea cervicornis agglutinin (HCA) on rat zymosan-induced arthritis (ZyA). Zymosan (50-500 µg/25 µL) or sterile saline (Sham) was injected into the tibio-tarsal joint of female Wistar rats (180-200 g). Arthritic animals received morphine (4 mg/kg, intraperitoneal), indomethacin (5 mg/kg, intraperitoneal), or 2% lidocaine (100 µL, subcutaneous). HCA (0.3-3 mg/kg) was administered by intravenous route 30 min before or 2 h after zymosan. 1H-[1,2,4]oxadiazolo[4,3-a]-quinoxalin-1-one (ODQ, 4 µg, intra-articular) was given 30 min prior HCA. Hypernociception was measured every hour until 6 h, time in which animals were sacrificed for evaluation of leukocytes of the intra articular fluid and gene expression of TNF-α, IL-1, IL-10, and iNOS in the joint tissues using PCR techniques. Hypernociception was responsive to morphine and indomethacin, and its threshold was not altered by lidocaine. The post-treatment of HCA reduced both hypernociception and leukocyte influx. This antinociceptive effect was abolished either by ODQ and glibenclamide. HCA also reduced gene expression of iNOS and TNF-α. In conclusion, the antinociceptive effect of HCA in ZyA involves cyclic GMP signalization and selective modulation of cytokine expression.

A novel vasorelaxant lectin purified from seeds of Clathrotropis nitida: partial characterization and immobilization in chitosan beads.

A novel lectin from seeds of Clathrotropis nitida (CNA) was purified and characterized. CNA is a glycoprotein containing approximately 3.3% carbohydrates in its structure. CNA promoted intense agglutination of rabbit erythrocytes, which was inhibited by galactosides and porcine stomach mucin (PSM). The lectin maintained its hemagglutinating activity after incubation in a wide range of temperatures (30-60 °C) and pH (6.0-7.0), and its binding activity was dependent on divalent cations (Ca(+2) and Mg(+2)). SDS-PAGE showed an electrophoretic profile consisting of a single band of 28 kDa, as confirmed by electrospray ionization mass spectrometry, which indicated an average molecular mass of 27,406 ± 2 Da and the possible presence of isoforms and glycoforms. In addition, CNA exhibited no toxicity to Artemia sp. nauplii and elicited reversible and dose-dependent vasorelaxation in precontracted aortic rings. CNA was successfully immobilized on chitosan beads and was able to capture PSM in solution. This study demonstrated that CNA is a lectin that has potential as a biotechnological tool in glycomics and glycoproteomics applications.

Analgesic activity of a polysaccharide in experimental osteoarthritis in rats.

Viscosupplementation efficacy has been related to the high molecular weight of hyaluronic acid-like compounds, as well as to gel formulation. We evaluated the effect of a galactomannan polysaccharide derived from Guar gum (GG) in joint pain in an osteoarthritis (OA) model. Wistar rats (six animals/group) were subjected to anterior cruciate ligament transection (ACLT-OA group). The OA group was compared to a false-operated group (sham). Joint pain was recorded daily, using the articular incapacitation test, until 7 days after ACLT. Solutions or gel preparations of GG (100 microg) or Hylan G-F 20 (100 microg), used as a comparator, were given intraarticularly (i.a.) at day 4 after ACLT. Controls received saline i.a. The OA group had significantly increased joint pain as compared to sham (P<0.001). GG, either as a gel or solution, significantly inhibited joint pain similar to the inhibition achieved with Hylan G-F20. This is the first demonstration that a galactomannan derived from GG reduces joint pain in experimental OA. This analgesia is independent of the colloidal state. We propose that the analgesic benefit of viscosupplementation may be due to an intrinsic carbohydrate-mediated mechanism rather than to the rheologic properties of the material.